(1) Field of the Invention
The present invention relates to a method for measuring the surface roughness of honeycomb structures, particularly, honeycomb structures for use in rotary regenerating type heat exchangers, and to surface roughness-measuring elements to be used therefor.
(2) Related Art Statement
Since honeycomb structures are used as catalyst carriers or the like in the state that they are fixedly assembled to catalyst units or the like, cut end faces of honeycomb structures used are left as they are cut.
On the other hand, since honeycomb structures recently have been used as regenerators for rotary regenerating type heat exchangers, it is necessary that an end face including a plurality of cut cells of the honeycomb structure sealingly contacts a sealant under rotation. Therefore, it is important to control the surface roughness of the end face of the honeycomb which includes a plurality of the cells.
Heretofore, the surface roughness has been measured by means of a surface roughness measuring device using a given stylus. That is, as shown by way of a measuring example in FIG. 4, unevenness of an object 31 to be measured is detected by bringing a given stylus 32 into contact with a surface of the object 31, and moving the stylus 32 along the surface of the object, while maintaining contact. FIGS. 5(a) and (b) show front and side views of a standard stylus, respectively, and FIGS. 5(c) and (d) show front and side views of a knife edge type stylus, respectively: As is seen in there figures, the stylus 32 having a substantially conical tip shape is connected to a tip of a measuring element body 33.
Although these styli 32 can be used with a steel plate or sheet, use with end faces of the above-mentioned honeycomb structures causes problems.
That is, when the above stylus 32 is traced on end walls of cells at the end face of the honeycomb structure having a cell wall thickness of about 0.1 mm, the stylus 32 falls in a through channel from the cell wall to make measurement impossible. Even if the end face of the honeycomb structure can be traced by the stylus, variations in the measured roughness of the end faces of the cell walls are so great as to make the accurate measuring impossible.
On the other hand, the roughness of the entire sliding surface, that is, the smoothness of the entire end face including a plurality of the cells, is more important rather than the roughness of each cell wall.